In the manufacture of glass articles, such as glass containers, various anomalies or variations can occur that affect the commercial acceptability of the containers. These anomalies, termed “commercial variations,” can involve one or more of numerous attributes of the containers. For example, commercial variations can include dimensional characteristics of a container at the container sidewall, the bottom or bearing surface, the container finish, or at the container sealing surface; they can also include variations such as stones or checks within the container finish, the sidewall or the bottom. It is conventional practice to mold indicia on each container that is indicative of the mold of origin of the container for inspection and quality control purposes. Thus, it is often useful to provide inspection equipment capable of inspecting the containers for commercial variations, mold indicia or other features that warrant inspection. The term “inspection” is used in its broadest sense to encompass any optical, electro-optical, mechanical or electrical observation or engagement with the container to measure or determine a potentially variable characteristic, including but not necessarily limited to mold codes and commercial variations.
U.S. Pat. No. 5,291,271 discloses an apparatus for measuring the sidewall thickness of transparent containers, which includes a source for directing a light beam onto the outer surface of the container sidewall at an angle such that a portion of the light beam is reflected from the outer sidewall surface, and a portion is refracted onto the container sidewall, reflected from the inner sidewall surface and then re-emerges from the outer sidewall surface. A lens is disposed between a linear array light sensor and the container sidewall for focusing light energy reflected from the outer and inner sidewall surfaces onto the sensor. The lens has an image plane in which the sensor is disposed and an object plane co-linear with the light beam. An information processor is responsive to light energy incident on the sensor for determining wall thickness of the container between the inner and outer sidewall surfaces.
U.S. Pat. No. 6,256,095 discloses an apparatus for inspecting the sealing surface area of a container finish that includes a light source positioned to direct a collimated line-shaped light beam (i.e., having a length dimension many times a width dimension) onto the sealing surface area of a container. The line-shaped light beam at the container surface area has a long dimension orthogonal to the container axis, and a narrow dimension tangential to the container axis. A light sensor is disposed to receive portions of the line-shaped light beam reflected from the sealing surface area, and provides an electrical output signal that varies with height or level of the sealing surface area with respect to the light source and sensor. A lens system is disposed to direct onto the light sensor only light energy reflected from the container sealing surface area in planes parallel to the common plane of the container axis and the sensor. The lens system and sensor together comprise a full imaging system for light energy reflected from the sealing surface in planes parallel to the common plane of the container axis and its sensor, but which is substantially immune from stray reflections, including reflections from other points on the container, that are not parallel to this plane.